Today I had the chance to dig into the Iron Fireman stoker I picked up from Greg (LsFarm) a few months ago along with an EFM 350 boiler top. That thread is here: http://nepacrossroads.com/about13071.html
I started out wiring a new cord to the motor as the original piece of wiring that was left was really crunchy. I wanted to test the "volumeter" and damper setup, check the coal feed, and change the gearbox oil. I got the motor running and everything seemed to be OK, but the draft damper seemed to be rusty and stiff. I sprayed some PB Blaster on the shaft pivots and it started to loosen up with some crunching noises. Finally, it got REALLY loose and I thought that's not good. While testing it, I also noticed very little airflow through the tuyeres, and that was after I removed the cleanout plug and vacuumed out the retort real well.
I decided that I had to pull apart the air tube/damper/volumeter setup and see what was going on. Amazingly, they used brass 4-40 nuts with the steel screws, so I only had 2 or 3 that I had to chisel off the head. It took a little wrangling but it came apart with not too much difficulty. I wasn't quite prepared for what I found, tho....
It was plugged solid with several decades of mouse nests, acorns, etc. Unfortunately, it rotted out the damper flap and corroded the rest of the works pretty badly. I pulled out some pretty big chunks of flat rusty "something" that I thought were sheet metal pieces, but I believe I've got everything accounted for and it was just layers of dirt, rust, and mouse pee.
The damper flap is shot, but it pivots on a brass shaft, so I just need to make a new flap and drill out the screws that hold it on and replace it. The rod that actuates the damper from the "volumeter" diaphragm is also brass and just needs to be cleaned up. They used a really simple clevis/cotter pin setup to connect the rod to the damper. Amazingly, the diaphragm inside is still flexible and in good shape! Here's what it is supposed to look like:
It's a really clever setup where the main adjustment just controls the amount of air that is sent to the diaphragm based on airflow - it is self regulating so as to maintain constant airflow to the fire. The air damper can be set and locked manually in case something goes wrong with the automatic system. Looking forward to see how well it actually works.
I also cleaned out the tuyere slots today and discovered that only the top slots have direct access to the airbox. The lower and middle slots have a "wall" that would look like a "J" in a section view behind them that allows air flow down and through the slots, but keeps the fines inside the burn area. It's a clever design touch where the air has to go up, over, and then down and out:
As if that wasn't enough, I decided that the motor sounded like it had bad bearings and had to come off. There are 4 bolts that hold the blower wheel to the pulley/hub piece. Once those are removed, the motor can be removed and the blower wheel stays in the shroud, and the pulley/hub removed with a puller. Indeed, the motor bearings (sleeve bushings) were shot - the pulley side bushing had a good .010 or .015 slop around the shaft. So, the motor came apart to see what might be able to be done with it. It all looked to be in excellent condition except the bushings - windings, centrifugal switch (contacts were caked up a little tho), temperature cutout (it's a sealed motor), and rotor look great. The shaft that rides in the pulley end bushing is a bit worn (.001 or .002 undersize) but I think it will be OK. It looks like the motor didn't receive very good lubrication back in the day. But they don't build motors like this anymore, so I'm going to drop the rotor and two end bells at a local motor repair shop to see what can be done with them. I'm sure it will cost less than a new motor because it's a 1/6hp capacitor start - smallest commonly available today is 1/4hp, and small capacitor start motors aren't very common (or cheap).
The only part of the job I actually completed without finding something wrong was the gearbox oil change. The 60+ year old stuff came out, looking pretty dark like molasses, but no water and no chunks.
I refilled it with Mobil 1 SHC 634 synthetic 140wt which is safe for bronze and brass gears unlike a GL-5 automotive gear lube.
I was pretty disappointed to find the extent of damage today, but at least it's pretty easily repaired. Fortunately, the important things are in great shape (tuyeres, auger, gearbox, and major sheetmetal), so once these few small items are taken care of, it will be ready for another 60 years.